The use of 6-amino-9-substituted benzyl purines and the N.sup.6 -alkyl derivatives thereof for the treatment of coccidiosis is well known (see U.S. Pat. No. 3,845,426 to Lira et al. issued 5 Nov. 1974 and Great Britain Pat. No. 1,534,163). In particular, the compound 6-amino-9(2-chloro-6-fluorobenzyl)purine is described as being particularly active and is sold under the generic name of arprinocid. The N.sup.6 -alkyl derivatives of arprinocid have been prepared in low yields by the direct alkylation of arprinocid and using the more complicated procedures of aminolysis of 6-chloro-9-substituted benzyl purines or N'-alkylation of arprinocid followed by base catalyzed Dimroth rearrangement to the desired N.sup.6 -alkyl-arprinocid. See the above British patent and the additional references of Wang et al. Biochemical Pharmacology, 28 2249-2260 (1979): K. Imai et al., European Journal of Medicinal Chemistry, 15 207-210 (1980). The instant procedure is an improvement over the prior art procedures in that the N.sup.6 -alkyl-arprinocid is prepared in overall yields in excess of 90% in two steps.